It is known, as disclosed in U.S. Pat. Nos. 3,549,999, 4,169,244 and 4,292,519 to test an electronic component, such as integrated circuits, with a scanning electron microscope which directs an electron beam in sequence to various points on parts of the electronic components. A current of secondary electrons is emitted in response to the impingement of the electron beam and converted into an electrical signal which is a measurement of values of an electrical parameter at the testing point.
However, most of the prior art apparatus has only had the capability of measuring an area of less than one centimeter because of resolution limitations. In order to measure larger areas of electronic components the components have been required to be moved relative to the beam. See IBM Technical Disclosure Bulletin, Volume 28, No. 8, Jan. 1986. One of the features of the present invention is the provision of a secondary electron collector which can accurately measure secondary electron emission over a large area, without moving the electronic component.
Another problem with prior art devices is that any variations in the beam current adversely affects the measurement results. Another feature of the present invention is the use of a combination blanking and Faraday cup for sampling and measuring the beam current when the beam is blanked thereby achieving better accuracy.
The present invention is also advantageous in that the electron beam may be used to measure the capacitance of networks in the electronic component.